implementing char* insted of vector

#include "iostream"
using namespace std;
#include "string"
#include "vector"


class Mint{
public:
	Mint();
	Mint(int);
	Mint(const char*);
	bool operator<(const Mint&);
	bool operator>(const Mint&);
	void afficher();
	void size();
private:
	char* num;
	int size;
};

#include "Mint.h"
#include "string.h"





Mint::Mint()
{
	taille = 1;
	num = new char[taille];
	*num = '\0';
}

Mint::Mint(const char* s)
{
	if(strlen(s)%2)
		num.push_back(s[0]-'0');
	unsigned int i;
	for(i=strlen(s)%2;i<strlen(s);i+=2)
	{
		int left = s[i] - '0';
		int right = s[i+1]-'0';
		num.push_back(0);
		num.back() = left << 4;
		num.back() |= right;
	}
}
bool Mint::operator<(const Mint& rhs)
{
	unsigned int i;
	if (num.size()<rhs.num.size())
			return true;
	if (num.size()==rhs.num.size())
	for(i=0;i<num.size();i++)
	{
		if(num[i] < rhs.num[i])
			return true;
	}
	return false;
}
bool Mint::operator>(const Mint& rhs)
{
	if (*this < rhs)
	 return false;
	return true;
}
void Mint::afficher()
{

	unsigned int i;
	for (i=0;i<num.size();i++)
	{
		int first_digit = (num[i] & '\xF0')>>4;
		int second_digit = (num[i] & '\x0F');
		if (i || first_digit) cout << first_digit;
		cout << second_digit;
	}
}
void Mint::size()
{
	cout << num.size();
}